Relating to network interconnectivity

ABSTRACT

The present disclosure relates to a communication method and system for converging a 5th-Generation (5G) communication system for supporting higher data rates beyond a 4th-Generation (4G) system with a technology for Internet of Things (IoT). The present disclosure may be applied to intelligent services based on the 5G communication technology and the IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services. Disclosed is a method of operating a telecommunication system operating in a multi-connectivity configuration, wherein a first node operates a first radio connection using a first Radio Access Technology, RAT, and a second node operates a second radio connection using a second RAT, wherein a User Equipment, UE, operable to communicate over first and second radio connections, is configured on the basis of its capabilities with respect to the first node and its capabilities with respect to the second node.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation application of prior application Ser.No. 17/163,970, filed on Feb. 1, 2021, which has issued as U.S. Pat. No.11,690,117 on Jun. 27, 2023, which is a continuation application ofprior application Ser. No. 16/318,985, filed on Jan. 18, 2019, which hasissued as U.S. Pat. No. 10,912,139 on Feb. 2, 2021, which is a U.S.National Stage application under 35 U.S.C. § 371 of an Internationalapplication number PCT/KR2017/007731, filed on Jul. 18, 2017, which isbased on and claims priority under 35 U.S.C. § 119(a) of a Britishpatent application number 1612428.1, filed on Jul. 18, 2016, Britishpatent application number 1613972.7, filed on Aug. 16, 2016, Britishpatent application number 1618640.5, filed on Nov. 4, 2016, and Britishpatent application number 1700242.9, filed on Jan. 6, 2017, thedisclosure of each of which is incorporated by reference herein in itsentirety.

TECHNICAL FIELD

The present invention relates to interconnectivity between differentcommunication networks. It particularly, but not exclusively, relates todual connectivity in communication networks where one network is LTE andthe other is Fifth Generation (5G).

BACKGROUND ART

To meet the demand for wireless data traffic having increased sincedeployment of 4G communication systems, efforts have been made todevelop an improved 5G or pre-5G communication system. Therefore, the 5Gor pre-5G communication system is also called a ‘Beyond 4G Network’ or a‘Post LTE System’. The 5G communication system is considered to beimplemented in higher frequency (mmWave) bands, e.g., 60 GHz bands, soas to accomplish higher data rates. To decrease propagation loss of theradio waves and increase the transmission distance, the beamforming,massive multiple-input multiple-output (MIMO), Full Dimensional MIMO(FD-MIMO), array antenna, an analog beam forming, large scale antennatechniques are discussed in 5G communication systems. In addition, in 5Gcommunication systems, development for system network improvement isunder way based on advanced small cells, cloud Radio Access Networks(RANs), ultra-dense networks, device-to-device (D2D) communication,wireless backhaul, moving network, cooperative communication,Coordinated Multi-Points (CoMP), reception-end interference cancellationand the like. In the 5G system, Hybrid FSK and QAM Modulation (FQAM) andsliding window superposition coding (SWSC) as an advanced codingmodulation (ACM), and filter bank multi carrier (FBMC), non-orthogonalmultiple access (NOMA), and sparse code multiple access (SCMA) as anadvanced access technology have been developed.

The Internet, which is a human centered connectivity network wherehumans generate and consume information, is now evolving to the Internetof Things (IoT) where distributed entities, such as things, exchange andprocess information without human intervention. The Internet ofEverything (IoE), which is a combination of the IoT technology and theBig Data processing technology through connection with a cloud server,has emerged. As technology elements, such as “sensing technology”,“wired/wireless communication and network infrastructure”, “serviceinterface technology”, and “Security technology” have been demanded forIoT implementation, a sensor network, a Machine-to-Machine (M2M)communication, Machine Type Communication (MTC), and so forth have beenrecently researched. Such an IoT environment may provide intelligentInternet technology services that create a new value to human life bycollecting and analyzing data generated among connected things. IoT maybe applied to a variety of fields including smart home, smart building,smart city, smart car or connected cars, smart grid, health care, smartappliances and advanced medical services through convergence andcombination between existing Information Technology (IT) and variousindustrial applications.

In line with this, various attempts have been made to apply 5Gcommunication systems to IoT networks. For example, technologies such asa sensor network, Machine Type Communication (MTC), andMachine-to-Machine (M2M) communication may be implemented bybeamforming, MIMO, and array antennas. Application of a cloud RadioAccess Network (RAN) as the above-described Big Data processingtechnology may also be considered to be as an example of convergencebetween the 5G technology and the IoT technology.

In prior art LTE configurations employing dual connectivity (DC) Release12 of the 3GPP standard specification, DC between two different LTE eNBsis standardised. However. in future releases, it will be possible tooffer DC between an LTE network and a 5G network as well as between twoor more 5G nodes. The 5G network in particular concerns a new radioaccess technology (RAT), that may include functionality unknown to theLTE network.

In particular, if a User Equipment UE supports LTE and 5G, then it isimportant that its radio connections are properly configured. Forexample, it may be that the radio hardware in the UE cannot fullysupport LTE and 5G simultaneously, meaning the network is unable toapply LTE and 5G configuration options independently but have to choosebetween a limited set of combinations supported by the UE. For example,some of the UE memory may be shared between the LTE and 5G connections,or it may not be possible to configure an LTE carrier on a particularfrequency band while at the same time the UE is configured with a NewRadio (NR) carrier on another particular frequency. Note that throughoutthis specification, the terms NR (New Radio) and 5G (Fifth Generation)are used interchangeably and are intended to refer to the samestandardised system.

For example, if a first node, the Master Node, MN, employs the LTE RATand a second node, the Secondary Node, SN, employs the 5G RAT, then itis possible that the nodes cannot mutually understand each other'sconfigurations. Similarly, an LTE MN may not comprehend the UE 5Gcapabilities. In order to ensure that the UE is not configured beyondits capabilities, co-ordination is required between the nodes involvedin DC. Embodiments of the present invention are arranged to facilitatethis coordination, moreover in a manner to achieve optimal performance.It is noted that most details of the 5G configuration and 5G UEcapabilities are not relevant for this UE capability coordination andhence it is preferable that an LTE MN is not required to comprehend suchinformation.

In broad terms, an objective of embodiments of the present invention isto coordinate different Radio Access Technologies (RAT), not only toensure the UE is not configured beyond its capabilities but furthermoreto maximise system performance. In particular, this should take accountof future, perhaps currently unknown, features.

DISCLOSURE OF INVENTION Technical Problem

Embodiments of the invention seek to negotiate alternative configurationoptions in case there are dependencies in UE capabilities between thetwo different networks, in particular an LTE and a 5G network.

Broadly, embodiments of the invention seek to configure networkconfigurations to maximise network throughput on the basis ofconfiguring LTE and 5G connections for a particular UE operating in a DCscenario.

It may not be possible in any particular case to configure the UE tomaximise throughput for both the LTE and the 5G connection and, if so, acompromise position will be adopted, which depends on the particularcircumstances prevailing.

Throughout this specification, the terms MN and SN refer to Master Nodeand Secondary Node respectively. These correspond to MeNB and SeNB asused in LTE systems or MgNB and SgNB as used in 5G systems. MCG and SCGrefer to Master Cell Group and Secondary Cell Group respectively, alsoas used in LTE. Inter-node procedures/messages: SNaddition/modification/release is a generalised term corresponding toSeNB addition (request, request ack), SeNB modification request and soon as used in LTE or SgNB addition and SgNB modification and son on asused in 5G.

When there is Dual Connectivity in use, there are 4 possible deploymentoptions:

TABLE 1 MN SN LTE LTE LTE NR NR NR NR LTE

Note that the MN manages the MCG and the SN manages the SCG.

Generally, it is desirable to provide flexibility in terms of support ofseveral functions dependent on band, band combination or even band ofband combination (i.e. capability signalling is complex). Further, it isalso generally desirable to share device capabilities e.g. transmitpower, memory, processing (as in case of DC).

In general, the network always attempts to respect the capabilities ofthe UE, i.e. the network does not try to instruct the UE to operate in amanner in which it cannot and the UE will reject commands which gobeyond its capabilities.

In the case of LTE DC, the features that the UE can support for SCG isimpacted by what is configured for MCG (and vice versa) i.e. the twonodes need to share UE capabilities. A primary case concerns bands/bandcombinations. There may be limitations or difficulties in attempting tosupport simultaneous configuration of cells in the same or similarfrequency range (i.e. from radio perspective or when they share RFhardware).

In the case of LTE DC, there is tight coordination between the nodes toavoid any conflicts.

Only the MN initiates addition of Secondary Cells, so the MN can ensurelimitations regarding bands/band combinations. For several high levelparameters, explicit signalling is used by which the MN can restrictwhat the SN can configure e.g. memory, transmit power, TB size in TTI.More detailed capability coordination is by implicit signalling i.e. MNprovides the MCG configuration, from which SN can determine moredetailed restrictions (i.e. detailed leftovers). The SN needs tocomprehend MCG configuration to derive these detailedlimitations/leftovers.

In case of LTE DC, it is assumed that the MN still has overallresponsible for ensuring that UE capabilities are respected. Theconfiguration set by the SN is transferred via the MN to the UE.Forwarding is not entirely transparent i.e. the MN is required tocomprehend the SCG configuration (and hence can verify if UEcapabilities are respected).

FIG. 1 shows a message exchange between the three entities involved in aDC configuration: the UE, the MN and the SN. The messages are labelled 1to 5 and are as follows:

1. The MN retrieves UE capabilities from the UE.

2. Typically a measurement report from the UE triggers configuration ofDC (i.e. the cell is good enough to be configured by SN)

3. The MN requests the SN to configure DC. Besides the mainconfiguration aspects decided by the MN (DRBs, SCells), the MN signalsparameters for capability coordination i.e. UE capabilities and MCGconfiguration, as well as some specific parameters (power coordination,TB-bits)

4. The SN signals the SCG configuration, that it selected based on theinputs provided by the MN, to the MN

5. The MN forwards the SCG configuration to UE. The MN maysimultaneously adjust the MCG configuration, which may be needed torespect UE capabilities

Solution to Problem

In general, embodiments of the invention provide: selection of anoptimal configuration while respecting UE capabilities; support for somelevel of UE capability sharing/dependencies (i.e. conflicts), whilenetwork nodes have maximal independence and require minimal inter-RATknowledge such as configuration and capabilities.

According to the present invention there is provided an apparatus andmethod as set forth in the appended claims. Other features of theinvention will be apparent from the dependent claims, and thedescription which follows.

According to a first aspect of the present invention, there is provideda method of operating a telecommunication system operating in amulti-connectivity configuration, wherein a first node operates a firstradio connection using a first Radio Access Technology, RAT, and asecond node operates a second radio connection using a second RAT,wherein a User Equipment, UE, operable to communicate over first andsecond radio connections, is configured on the basis of its capabilitieswith respect to the first node and its capabilities with respect to thesecond node.

In an embodiment, the UE reports to the first node how its capabilitieswith respect to the first node are related to its capabilities withrespect to the second node and support of a particular capability withrespect to the first node is dependent on use of the particularcapability with respect to the second node.

In an embodiment, the UE reports to the first node a subset of possiblecapabilities with respect to the second node.

In an embodiment, the subset of possible capabilities is in a formatwhich is comprehensible by the first and second node.

In an embodiment, the first and second node communicate regarding theconfiguration of the UE, via a backhaul connection.

In an embodiment, the first and second node communicate regarding theconfiguration of the UE, via the UE.

In an embodiment, the UE indicates a shared resource to the first node,the first node indicates to the UE how much of the shared resource is tobe allocated to the second node and the second node requests a differentallocation if required.

In an embodiment, the shared resource may be a shared buffer or abaseband processing capability.

In an embodiment, the first node negotiates the UE configuration withthe second node on the basis of maximizing a selected parameter.Preferably, the selected parameter is data throughput. Preferably, thedata throughput is weighted by one or more of UE cost and system cost.

In an embodiment, the first node indicates to the second nodeconfiguration restrictions regarding the second radio connection relatedto the UE capability dependencies, whereby the indication of theconfiguration restriction concerns a subset of the radio configurationor refers to an option in the UE capabilities indicating what the UE mayor may not support in the form of an index. The index, in this context,is a means to indicate which bands or BCs the SN can or cannotconfigure. Furthermore, the information regarding what the index refersto is included in LTE capabilities (i.e. as used by MN to decide whensetting the index) and possibly in NR capabilities (as used by SN wheninterpreting the index).

In an embodiment, one of the first node and second nodes is operableaccording to an LTE standard and the other of the first and second nodesis operable to a 5G standard.

In an embodiment, a plurality of second nodes is provided. For example,there may be a single master node and plurality of secondary nodes.

In an embodiment, if the first node negotiates a configuration optioncomprising a particular combination of a first radio connectionconfiguration option and a second radio connection configuration option,then the second node indicates a different configuration option, ifrequired.

According to a second aspect of the present invention, there is provideda telecommunication system comprising a first node, a second node and aUE, all operable according to the first aspect.

According to a third aspect, there is provided a network node operableaccording to the first aspect.

According to a fourth aspect, there is provided a User Equipmentoperable according to the first aspect.

According to a fifth aspect, there is provided method of operating atelecommunication system operating in a multi-connectivityconfiguration, wherein a master node operates a first radio connectionto a UE using a first Radio Access Technology, RAT, and a secondary nodeoperates a second radio connection to the UE using a second RAT, whereinthe master node decides configuration restrictions to be applied by thesecondary node in connection with the second radio connection to the UE.

Advantageous Effects of Invention

In embodiments of the present invention, the Issue of dependency is samei.e. the UE LTE capabilities are likely to be impacted by certainconflicting 5G configurations. A primary case concerns bands/bandcombinations in the same/similar frequency range, as these may not bepossible to configure simultaneously from the radio perspective or whenthey share RF hardware. Furthermore, UE providers typically prefer toshare other device capabilities such as. transmit power, memory,processing.

For the case of IRAT DC, there are some differences from the prior artdiscussed above. It is generally desirable is that the network nodesinvolved should be able to set the configuration of its RAT asindependently as possible, i.e. without reference to the other nodes.The 5G node should decide which cells to configure, based onmeasurements it configures the UE to perform, rather than the MNinitiating SCG cell addition. Additionally, nodes should not be requiredto comprehend each others configuration (as in the prior art LTE DC).Similarly, nodes should not be required to fully comprehend UEcapabilities concerning another RAT.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a prior art message exchange in a DC configuration;

FIG. 2 shows a message exchange according to an embodiment of thepresent invention;

FIG. 3 shows a message exchange according to an embodiment of thepresent invention;

FIG. 4 shows a message exchange according to an embodiment of thepresent invention;

FIG. 5 shows a message exchange according to an embodiment of thepresent invention;

FIG. 6 shows a message exchange according to an embodiment of thepresent invention;

FIG. 7 shows a message exchange according to an embodiment of thepresent invention;

FIG. 8 shows a message exchange according to an embodiment of thepresent invention;

FIG. 9 shows a message exchange according to an embodiment of thepresent invention;

FIG. 10 shows a message exchange according to an embodiment of thepresent invention;

FIG. 11 shows a message exchange according to an embodiment of thepresent invention;

FIG. 12 shows a message exchange according to an embodiment of thepresent invention;

FIG. 13 shows a table related to FIG. 12 ;

FIG. 14 shows a message exchange according to an embodiment of thepresent invention;

FIG. 15 shows a message exchange according to an embodiment of thepresent invention;

FIG. 16 shows a message exchange according to an embodiment of thepresent invention;

FIG. 17 shows a table illustrating conflicting configurations;

FIG. 18 shows a table illustrating a selection in the case of 1conflict;

FIG. 19 shows a table illustrating a selection in the case of 2conflicts;

FIG. 20 shows a table illustrating a continuous selection scheme;

FIG. 21 shows a message exchange according to an embodiment of thepresent invention;

FIG. 22 shows a message exchange according to an embodiment of thepresent invention;

FIG. 23 shows a message exchange according to an embodiment of thepresent invention;

FIG. 24 shows a message exchange according to an embodiment of thepresent invention;

FIG. 25 shows a message exchange according to an embodiment of thepresent invention;

FIG. 26 shows a message exchange according to an embodiment of thepresent invention; and

FIG. 27 shows a general network schematic according to an embodiment ofthe present invention.

MODE FOR THE INVENTION

Embodiments of the present invention provide an optimal configuration incases of UE capability sharing/dependencies (i.e. conflicts). In oneexample, this can relate to bands or band combinations, but otherscenarios exist too.

In one embodiment, the network nodes detect dependencies/conflicts. TheUE informs LTE network (eNB) within LTE capabilities how its LTEcapabilities are impacted by conflicting 5G configurations. Likewise 5Gradio network is informed within 5G UE capabilities. The Impact ofconflicting 5G configuration could be: non-support, reduced support(e.g. lower value/performance).

In another embodiment, the MN decides either by setting minimumcriterion or relies on assistance from secondary node. The decision mayprimarily be based on achievable data throughput, as a measure ofperformance. This may be weighted by system cost (e.g. required networkresources) and/or UE cost (e.g. battery consumption). Other aspects mayalso be considered e.g. if service that a UE wants to receive isprovided on limited carriers i.e. a throughput-based decision may belimited to equal carriers.

In another embodiment, nodes are aware of the configuration supported byeach other (e.g. bands/carriers). Options regarding roles ofmaster/secondary node include: only MN initiates the setup ofconflicting configurations; and both nodes may initiate setup ofconflicting configurations.

FIG. 2 shows a message exchange depicting network awareness of UEcapability sharing/dependencies. The issue addressed here concerns howthe network becomes aware that UE capabilities are shared between LTE(MN) and NR (SN). In other words how does it know that there aredependencies and, hence, it needs to decide/select between conflictingconfiguration options.

In the embodiment of FIG. 2 , the UE informs LTE network (eNB), inmessage 2, within LTE capabilities how its LTE capabilities are impactedby conflicting 5G configurations. Likewise the 5G radio network isinformed within 5G UE capabilities. The impact of conflicting 5Gconfiguration could be: non-support, reduced support (e.g. lowervalue/performance). This conforms to the general principle that anetwork node should not be required to investigate other RATscapabilities/signaling.

FIGS. 3 to 5 concern an MN-initiated SCG modification e.g. addition ofone or more SCells. For instance, when requesting the SN to add SCell(s)for which the MN will have to limit the MCG configuration (i.e. a‘conflicting config’), the MN provides a minimum criterion. If the SCGcan meet this, it will simply configure such SCell(s). If not, it willnot configure but will return a failure message with an achievablecriterion,

FIG. 3 shows a message exchange depicting a general mechanism forcoordination between nodes. The issue addressed here is how do thenetwork nodes coordinate their configurations in case there are UEcapability dependencies and, hence, there is a need to decide or selectbetween conflicting configurations. FIG. 3 illustrates, in a generalform, the high level interaction.

In the embodiment of FIG. 3 , the Master acts in one of two ways,depicted in the left hand and right hand part of FIG. 3 , respectively:

A) by setting minimum criterion (left side of FIG. 3 ) i.e. MNdelegated: the MN delegates the actual check to the SN) i.e. the SNperforms the evaluation of the criterion and if not met, the SN willinitiate release of the conflicting configuration; or

B) based on assistance from the secondary node (right side of FIG. 3 )i.e. MN based: the MN performs the actual check based on assistance SNi.e. the MN merely asks the SN to report and it is the MN that decideswhether to initiate release or not.

The decision may be primarily based on achievable data throughput. Itmay be weighted by system cost (e.g. required resources) and/or UE cost(e.g. battery consumption). Other aspects may also be considered e.g. ifservice a UE wants to receive is provided on limited carriers i.e. athroughput-based decision may be limited to equal carriers.

In general, nodes are aware of the configuration supported by each other(e.g. bands/carriers). There are various options regarding the role ofthe SN with respect to conflicting configurations:

a) Only the MN initiates setup of conflicting configurations

b) Both nodes may initiate setup of conflicting configurations

c) Whether the SN may initiate setup of conflicting configurations couldeither be fixed in standards, or configured by the MN

SN initiated modification could be performed in 1 or 2 steps:

-   -   1 step: SN modification request may be confirmed immediately        (e.g. in case an achievable condition is met)    -   2 step: a sequence with an MN initiated procedure nested in the        middle of the SN initiated procedure may be used in specific        cases

For the handling of conflicting configurations, the Table 2 belowsummarizes elementary procedures and their use:

TABLE 2 Initiate conflicting configuration Notes Master Always used butin case the MN performs actual check initiated SCG of criterion, thechanges, compared to the procedures modification used in LTE DC, may belimited (i.e. to triggering conditions and possibly to indication ofconfigurations that can/cannot be initiated by the SN) Secondary nodeUsed only if the SN is allowed to initiate modification initiated SCG ofconflicting configurations modification One or two step variants, as setout above Assistance Used only if the MN performs the actual check ofprocedure criterion based on assistance from the SN

FIG. 4 shows a message exchange in connection with an MN initiatedreconfiguration. The messages exchanged are numbered and 1 and 2:

1: SCG or SN Modification Request

The MN may indicate configurations that are or are not allowed to beinitiated by the SN (SCG establishment/modification). When requestingthe SN to add one or more conflicting configurations, the MN mayindicate a minimum criterion to be met for each configuration (MNdelegates evaluation)

2: SCG or SN Modification Request Acknowledgment (Ack)

The SN may indicate an achievable criterion to be met for each one ormore conflicting configurations for which the MN has indicated a minimume.g. when it has almost achieved the minimum value (MN delegatesevaluation)

It is instructive to consider an example of a conflict. Consider an LTEband or Band Combination (BC) that the UE only supports if certain 5Gband or BC, supported by the UE, is not configured alongside. Theminimum criterion may be defined as minimum average achievablethroughput.

The same sequence applies for SCG establishment i.e. SN additionrequest/request ack. Also note that the messages shown include otherparameters (not listed for clarity purposes).

FIG. 5 illustrates a message exchange in the case of SN assistance. Themessages labelled 1 and 2 are in addition to those shown in FIG. 4 :

1: SCG or SN Assistance Request

The MN may indicate configurations for which it wants the SN to providesome assistance information. The MN may include some configurationparameters e.g. regarding what information the SN should measure, whatto report and when to trigger a report (e.g. periodical or when acertain event condition is fulfilled)

2: SCG or SN Assistance

The SN reports the requested information for one or more of theconfigurations for which the MN requested it to provide assistance. Forexample, it should periodically report the achievable throughput for aparticular 5G band or BC.

The embodiments of FIGS. 4 and 5 concern a case in which there is noupfront bare minimum criterion. In such a case the SN, within themodification request, indicates an achievable criterion. Based on this,the MN decides whether to accept or reject the request. When accepting,it sets a minimum criterion, which indicates that the SN should releasewhen this cannot be met anymore.

FIG. 6 illustrates a message exchange in relation to a 1 step SNinitiated reconfiguration. The messages are labelled 1 and 2:

1: SCG or SN Modification Required

When requesting the MN to add one or more conflicting configurations,the SN indicates an achievable criterion.

2: SCG or SN Modification Confirm

The MN indicates a minimum criterion to be met for each one or more ofthe conflicting configurations that the SN has requested to add. The MNalso confirms establishment of the conflicting configurations that theSN requested to add. This confirmation may be implicit.

Consider an LTE band or Band Combination (BC) that the UE only supportsif certain 5G band or BC, supported by the UE, is not configuredalongside. The minimum criterion may be defined as minimum averageachievable throughput.

FIG. 7 illustrates a message exchange in relation to a 2 step SNinitiated reconfiguration. The messages are labelled 1 and 2:

1: SCG or SN Modification Required

When requesting the MN to add one or more conflicting configurations,the SN indicates an achievable criterion (as per FIG. 6 )

The MN initiates MN-initiated SCG modification. As part of thisprocedure, the MN indicates a minimum criterion to be met for each oneor more of the conflicting configurations that the SN requested to add.

2: SCG or SN Modification Confirm

The MN confirms establishment of the conflicting configurations that theSN requested to add, possibly by absence (i.e. when only indicating theconfigurations which modification failed)

Consider an LTE band or Band Combination (BC) that the UE only supportsif certain 5G band or BC, supported by the UE, is not configuredalongside. The minimum criterion may be defined as minimum averageachievable throughput.

For each LTE band or BC, consideration is given to the impact ofconfiguring a dependent 5G band or BC. Signaling herein is illustratedfor the simplest case i.e. impact of configuring 5G band or BC is thatLTE band or BC becomes non-supported. Absence of the impact info impliesthat the concerned LTE capability is not affected by 5G i.e. there areno dependencies.

Note that another option according to an embodiment of the presentinvention is more generally reduced support rather than non-support.

RF parameters referred to in messages (i.e. indicating how UE LTEcapabilities are affected by 5G) may include:

List of conflicting 5G bands i.e. a list separate from the list ofsupported bands within IRAT-Parameters may be indicated (particularlyuseful in case only a few of the 5G bands conflict with LTE bands orband combinations)

List of Conflicting 5G Band Combinations

Supported LTE bands (as in supportedBandListEUTRA), which is a list ofsupported bands, and for each indication of functionality which supportis band specific, and for each:

List of conflicting 5G bands is, for example, a BIT STRING with a firstbit referring to a 1st conflicting 5G band either indicated in a list ofsupported bands within IRAT-Parameters (or, by a separate list ofconflicting bands as described above).

List of conflicting 5G BCs is for example, a BIT STRING with a first bitreferring to a 1st BC in a list of conflicting 5G band combinations.

Supported LTE band combinations (as insupportedBandCombination(Reduced)) is a list of supported BCs, and foreach LTE BC (same as for each LTE band):

-   -   a list of conflicting 5G bands; and    -   a list of conflicting 5G BCs.

In certain cases, the IRAT parameters may include a list of supported 5Gband combinations e.g. in case of a UE may be connected to an LTE MN andmore than one 5G MN. If the IRAT parameters include such list, theconflicting 5G band combinations may or may not be indicated separately(alike for conflicting 5G bands).

In the embodiments described so far, each node detects capabilitydependencies by itself, based on its own capabilities. This is achievedby including information about dependencies or conflicting otheraggregated RAT configuration inside the UE capabilities. While thisapproach works, there are further improvements which are possible andwhich are described in the following embodiments.

In particular, it can be difficult to indicate the dependencies at asuitable detailed level. Also, there can be some duplication of theinformation if, for example, the same information appears in thecapabilities of each aggregated RAT.

In an embodiment, there is a general preference that nodes should not berequired to comprehend the configuration of the other cell group whichuses a different RAT e.g. the LTE node should not be required tounderstand the configuration of the related 5G node.

One means of addressing this is to introduce a common part of a messagewhich is understood by the nodes of both types of RAT. This may be doneas part of the MCG/SCG radio configuration. However, embodiments of thepresent invention introduce common UE capabilities which are alsoexchanged over radio interfaces.

Embodiments of the invention introduce a UE capability informationcontainer covering parameters concerning the case of aggregation withmore than one RAT involved. The relevant UE capabilities are signaledindependently. The relevant UE capabilities may be used for parametersrelevant for (and requiring comprehension by) nodes of each involvedRAT.

For example, in case of LTE-5G DC, the common UE capability containerwould cover capabilities to be comprehended by LTE and 5G nodes,typically used for dependent LTE-5G UE capabilities. In such anapproach, a network node only needs to comprehend the UE capabilities ofthe other RAT that are included in this common container. I.e. othercapabilities that are contained in the LTE and 5G capability containersonly need to be comprehended by the network node of the concerned RAT.

For example, in case of LTE-5G DC, the common UE capability containermay cover the band combinations comprising LTE and 5G bands. Related tothis, it is noted that currently there is a lot of flexibility regardingUE capabilities e.g. the support of a certain parameter may be specificto a band, a band combination or even to a band of a band combinationentry. When using a common capability, it appears straightforward tosupport such flexibility also for band combinations comprising LTE and5G bands.

As indicated previously, the LTE DC based approach for UE capabilitycoordination approach would require the network nodes to fullycomprehend UE capabilities and configurations corresponding to the otherRAT, which embodiments of the invention aim to avoid or minimize. Theconcept of separating or grouping the part that is to be comprehendedfrom the part that need not be comprehended can also be used for therelevant radio configurations. In other words, a separate common fieldconfiguration may be used also. A further step, requiring even lesscomprehension, is to use an index as described later.

FIG. 8 shows a message exchange relating to the transfer of capabilityinformation from the UE to the MN. There are 3 messages labelled 1 to 3:

-   -   1: The MN requests the UE to provide the capabilities of any RAT        combinations for which it may configure aggregation i.e. IRAT DC        capabilities (the common capabilities).    -   2: The UE provides the requested capabilities to the MN. The        capability information is used by the eNB to detect any        dependencies or conflicts regarding the UE support of the        configurations of the aggregated RATs (as in the previous        embodiments).    -   3: The MN forwards the received IRAT DC capabilities relevant        for the SN i.e. combinations including the RAT of the SN.

The SN may also retrieve the IRAT DC capabilities from the UE i.e. whenthe option of signaling via the direct interface is available i.e.directly between the UE and SN, rather than via the MN.

The MN and the SN use the IRAT DC capabilities to determine any(potential) capability dependencies or conflicts.

If at least partial comprehension of IRAT DC configuration is supported,the information could also be used for UE capability dependency orconflict resolution i.e. when a scheme more like LTE DC is used, ratherthan the one described in previously described embodiments.

FIG. 9 shows an alternative message exchange related to transfer ofcapability information. There are 2 messages, labelled 1 and 2. Withrespect to comprehension of the radio configuration information, thisscheme is more similar to LTE DC.

In this embodiment, the MN and the SN again use the IRAT DC capabilities(i.e. common UE capability container) to determine any (potential)capability dependencies or conflicts. The SN determines what it canstill configure for the SCG based on IRAT DC UE capabilities and on(part of the) MCG configuration. This requires the NR SN to comprehend(part of) the LTE MCG configuration.

In this scheme, the MN is also assumed to comprehend the SCGconfiguration, as it needs to know for which MCG reconfigurations italso needs to invoke a reconfiguration of the SCG.

The part that needs to be comprehended concerns the conflicting ordependent configurations e.g. concerning LTE bands or band combinationsthat the UE cannot handle alongside certain NR bands or bandcombinations.

To facilitate comprehension, the part that needs to be comprehended bythe other RAT node may be signaled by a separate field i.e. to limit theamount of other RAT information related configuration to becomprehended.

The embodiment shown in FIG. 9 shows the case of an SN initiated SCGreconfiguration, but it is understood that this is just one example.

The messages exchanged are:

1: The SN Initiates a Modification of the SCG Configuration Towards theMN.

The SN provides the SCG configuration that it intends to configure. TheSN may only initiate SCG configuration changes that do not require MCGconfiguration changes i.e. those which are possible with the UEcapabilities remaining, given the current MCG configuration.

The MN evaluates the SCG reconfiguration and initiates an RRC connectionreconfiguration towards the UE. In case the SCG reconfiguration is notpossible with the UE capabilities remaining, given the current MCGconfiguration, the MN may initiate MCG reconfiguration. This would beincluded in the same Uu message as an SCG reconfiguration, with jointsuccess or failure.

2: The MN Confirms the SCG Reconfiguration.

The MN confirms the reconfiguration and may include the MCGconfiguration, possibly only if it has changed.

FIG. 10 illustrates a message exchange related to an upfrontconfiguration of a bare minimum criterion. There are 2 messagesidentified.

Upon configuring IRAT DC, the MN provides the minimum criterion for allconflicting configurations (that the SN may initiate) i.e. an upfrontcriterion.

An aim of this approach is to suppress SN-initiated requests that willnever be accepted by the MN i.e. the SN only initiates the conflictingcriterion when it can meet the upfront minimum criterion. In otherwords, the upfront criterion may concern a more general bare minimumwhich could be signaled or fixed in some way e.g. by OAM. Note that theMN may set the value of the minimum criterion depending on the actualMCG settings.

1: The MN Initiates Establishment of the SCG/SN

MN configures an upfront or bare minimum criterion for each potentialconflicting criterion.

2: The SN Acknowledges Successful Establishment of the SCG/SN

Whenever detecting the need for an SN-initiated modification involvingcapability conflicts, the SN verifies if the upfront or bare minimumcriterion is met. Only if this is the case, will the SN request the SNmodification resulting in the concerned conflicting configuration.

FIG. 11 relates to a message exchange related to L2 buffer sizecoordination. It has been proposed that Buffer sharing should besupported, with a preferred solution involving a semi-static split. Onepossible approach is that the MN assigns a percentage e.g. that SN mayuse up to 75% of the UE's total L2 buffer size for NR, i.e. theremaining 25% would then be available for MN/LTE radio connection.

It is at present unclear how the nodes may interact precisely inpractice and, in particular, how to negotiate the split. In this respectit should be noted that for the LTE MN may be difficult to predict thesystem benefit when allocating a larger share to the 5G SN as this mayrequire detailed knowledge of 5G. This, in particular, applies whennegotiating about conflicting bands or band combinations, for which theachievable throughput may depend on detailed UE and SN capabilities. Anegotiation procedure is disclosed by which it is possible to avoid suchdetailed knowledge about another RAT i.e. by exchanging a simpleparameter e.g. achievable throughput.

In order for the nodes to interact or negotiate, it is possible to usean X2 based procedure i.e. to align with coordination of other aspects.Here, the MN decides and signals the L2 buffer size to be used for NR(e.g. a percentage). When the SN wants more, it indicates the requestedL2 buffer share and some assistance e.g. the corresponding achievablethroughput gain. This involves the exchange of simple parameters acrossX2 to avoid awareness of other the RAT's configuration.

Initially, i.e. upon SCG establishment, the MN merely sets a value whilenot yet having SN assistance.

The UE indicates the total L2 buffer size to MN by extending theexisting LTE capability field with new or larger values. When IRAT DC isnot configured, the entire memory available for L2 buffers may be usedfor LTE.

Alternatively, a new field may be introduced e.g. to include valuesbeyond what is sensible to use in LTE.

FIG. 12 shows a message exchange in connection with baseband processingcoordination.

In LTE, UE capabilities concerning baseband processing related functions(e.g. MIMO layers, simultaneously configurable carriers, CSI processes,NAICS resources) are specified per supported band combination. It hasbeen acknowledged that to avoid excessive signaling, it is desirable topull such baseband related capabilities out of the supported bandcombinations i.e. by specifying baseband processing capabilitiesseparate from RF related capabilities. In particular when this is done,it may be possible for the MN to semi-statically allocate a split ratioe.g. indicate that SN can use 70% of the UE's general purpose basebandprocessing. It has been agreed that the LTE MeNB should not be requiredto comprehend the SCG configuration and, generally, it is desirable toavoid awareness of the NR SCG configuration details. However, somelimited awareness appears acceptable and may be unavoidable.

In order for the nodes to interact or negotiate, it is possible to usean X2 based procedure i.e. to align with coordination of other aspects.Here, the MN decides and signals the baseband processing share to beused by the SN for 5G (e.g. a percentage). When the SN wants more, itindicates the requested baseband processing share and some assistancee.g. the corresponding achievable throughput gain.

Potential options for the desired baseband processing include: basebandprocessing level, total configured bandwidth, and total achievablethroughput.

Simple parameters are exchanged across X2 to avoid awareness of otherRAT configuration. Initially, i.e. upon SCG establishment, the MN merelysets a value while not yet having SN assistance.

Within LTE capabilities, the UE indicates how specific capabilities areaffected by reduced baseband processing. For example, the value of anLTE capability may decrease with 10 for every increase of 50 Mbps in NRthroughput. This is illustrated in the table of FIG. 13 which shows someexample figures for the above scheme.

Within the configuration, the MN indicates the baseband processing shareavailable for each RAT.

FIG. 14 shows a message exchange in connection with a negotiationprocedure.

The MN and the SN are aware of conflicting configurations from theirnative capabilities (left hand figure). The SN provides assistanceinformation about (potentially) conflicting SCG configuration(Achievable Throughput, AT). The MN sets requirement for conflicting SCGconfiguration (Required Throughput, RT). The SN continuously evaluatesthe RT set by MN.

Continuous evaluation of the criterion (e.g. throughput) is not deemednecessary and a one shot operation is preferable. However, continuousevaluation may be used if desired in a particular scenario.

For any cell used by the MN as an SCG cell, the SN continuously informsthe MN about significant load changes which are non UE-specific. This issupported by X2 presently.

It is possible to predict, based on cell load, how throughput evolvesfor a given configuration. However, throughput may suddenly drop whenoverload affects network's abilities e.g. MIMO layers. Achievablethroughput is UE specific i.e. it depend on the capabilities of aspecific UE.

An alternative embodiment provides a signaling throughput value perconflict. There is no partial success or failure. The reconfigurationinitiator may avoid troublesome reconfigurations cases by. includingspecific multiple conflicts combinations.

Signaling multiple throughput values is advantageous. With a singlethroughput value, a reconfiguration involving 2 independent conflictsmay succeed even if one of the conflicting reconfigurations may actuallyresult in throughput degradation, i.e. when it is more than compensatedfor by the other conflicting reconfiguration. Multiple values facilitateinforming the peer about what failed, enabling avoidance of same issuewhen retrying, thereby saving time and resources.

Consider the case where the MN initiates a conflicting reconfiguration,for example the addition of a 4G cell requiring the release of a 5Gcell. Within the request, the MN indicates the throughput gain (delta)it can achieve with the conflicting MCG reconfiguration. The SN rejectsthe reconfiguration if the throughput loss (delta) involved with the SCGreconfiguration needed to facilitate the MCG reconfiguration exceeds thethroughput gain indicated by MN. i.e. it rejects if the 5G cell to bereleased would result in more throughput than the 4G cell that the MNwishes to add. The MN may avoid reconfigurations that are likely to faile.g. by estimating, amongst other factors, the associated SCGreconfiguration loss based on Xn load information.

Consider the case of SeNB-initiated conflicting reconfiguration, forexample, the addition of a 5G cell requiring the release of a 4G cell.Within the request, the SN indicates the throughput gain (delta) it canachieve with the conflicting SCG reconfiguration. The MN rejects thereconfiguration if the throughput loss (delta) involved with the MCGreconfiguration needed to facilitate the SCG reconfiguration exceeds thethroughput gain indicated by SN. The SN never stops itself fromrequesting potentially conflicting configurations. The MN does notsignal RT unless there is an actual conflict, as the RT value may onlybe used at a particular moment in time.

Certain configuration information needs to be exchanged between thenodes. If the SN provides information upon initiating any potentialconflict, the MN could provide it only upon initiating actual conflicts.However, a preferred option is to require that the node initiating thepotential conflict provides information to its peer. Other configurationinformation need not be exchanged e.g. regarding cells not involved inany conflict.

When it is necessary to indicate conflicts, it is important to ensurethat the nodes understand the communications, which means that a commonlanguage or protocol is required.

One approach is to use the DC model i.e. initiator indicates itsproposed configuration: e.g. the MN indicates the 4G bands conflictingwith 5G bands that may be configured.

Another approach is the HO model i.e. the source adjusts to the target:e.g. MN indicates conflicting 5G bands.

The DC model involves somewhat more work for receiver as it still needsto process UE capabilities to determine the conflicting configuration.

The signaling overhead appears insignificant, with no clear andsignificant differences between the two approaches. For instance, onesource configuration might conflict with multiple target configurations,or multiple source configurations could conflict with the same onetarget configuration.

In an embodiment of the invention, Indices might be used, referring tospecific entries in UE capabilities. In case the LTE node indicates theconflicting NR band or BC, it need not really know the details (e.g.ARFCN) of the conflicting NR band or NR BC as it only needs a means toidentify the conflicting NR band or BC across Xn. The same applies forthe case where LTE MN indicates configured conflicting LTE band.

LTE capabilities will include:

List of conflicting NR bands e.g. 1: 5B1 (example)

List of conflicting NR BCs e.g. 1: 5B1+5B2 (5BC2), 2: 5BC1+5B2+5B3(5BC5)

NR capabilities could either Include exactly same lists of conflictingLTE bands (e.g. 1: 4B2) & BCs (1: 4B1+4B2, 4BC1, 2: 4B2+4B3, 4BC5) orinclude conflicting bands in the same order at the start of a regularlist of supported bands or BCs.

FIG. 15 illustrates a message exchange in connection with anMN-initiated reconfiguration. There are three messages indicated: 1, 2a,2b.

1. SN Modification Request

The MN provides a list of any potential conflicts such as any that mayrequire SCG re-configuration. The MN further indicates the acceptablethroughput loss i.e. a single value, or one per potential conflict.

2a. SN Modification Request Ack

No information transferred i.e. no partial success

2b. SN Modification Reject

In case a throughput value is provided per conflict, the SN rejects onlythe conflict(s) which fails the throughput criterion. Otherwise, in thecase of a single value, the MN either accepts or rejects all the(conflicting) configuration.

FIG. 16 illustrates a message exchange in connection with anSN-initiated reconfiguration. There are three messages indicated: 1, 2a,2b.

1. SN Modification Required

The MN provides a list of any potential conflicts such as any that mayrequire MCG re-configuration. The MN indicates the achievable throughputi.e. a single value, or one per potential conflict.

2a. SN Modification Confirm

No information transferred i.e. no partial success

2b. SN Modification Reject

In case a throughput value is provided per conflict, the SN mightindicate the conflict which fails the throughput criterion.

Embodiments of the invention may implement continuous evaluation, asreferenced previously. In particular action may be taken on not meetingthe throughput conditions which are chosen. A preferred action is thatthe SN initiates a release of a conflicting configuration. This issimple to implement since no further throughput negotiation is required,but the MN should ensure that the RT is always up to date. Anotherpossible action is that the SN reports a failure to meet the RT.

Further options are possible. These include:

-   -   a) The SN may initiate establishment of conflicting SCG        configuration only if its AT exceeds the RT, if previously set        by the MN.    -   b) The MN may initiate release of conflicting SCG configuration        based on previously indicated AT.    -   c) At any time, the MN and SN may provide update values of RT        and AT.    -   d) In case of a collision, the MN or SN may reject, based on the        updated AT and RT values just provided.

FIG. 17 shows a table which illustrates an example of conflictingconfigurations, which may be used to evaluate embodiments which will bedescribed shortly. Note that in the table, 4 refers to LTE, 5 refers to5G, B refers to band, and BC refers to Band Combination.

Conflicting bands are 4B2-5B1.

Conflicting BCs are 4BC5-5BC2, 4BC1-5BC5.

To allow 5BC2, the MN can give up a cell on 4B2 or on 4B3. It would thenset throughput criterion according to the amount it potentiallysacrifices as a result.

In the case of a continuous evaluation scheme, according to someembodiments of the invention, the MN may adjust TR dynamically,depending on alternatives that are available.

FIG. 18 shows a table illustrating various options in a single conflictsituation, by referring back to the table in FIG. 17 .

The mechanism according to an embodiment of the invention enables theselection of the option which provides the highest throughput. In allcase, the MN and SN are able to determine the throughput differencebetween the two options (option 1 and option 2).

In the first scenario, labelled ‘choose’, option 1 is to add an SCG cellon 5B1 and release an MCG cell on 4B2. Option 2 is to keep the MCG cellon 4B2 and not add an SCG cell on 5B1. ‘Choose’ indicates that a choicehas to made between these 2 options. Choose indicates that a choice hasto made between these 2 options. The comparison which is performed is toassess the gain of an SCG cell compared to the loss of an MCG cell.

In the second scenario, labelled ‘divert’, option 1 is to add an MCGcell on 4B2 and divert an SCG cell to 4B3. Option 2 is ‘no change’. Thecomparison which is performed is to compare the gain of an MCG cell withthe loss associated with the diversion of the SCG cell.

In the third scenario, labelled ‘Divert with side effect’, option 1 isto add an MCG cell on 4B2 and divert SCG cell 1 to 4B3 while reducingSCG cell 2 bandwidth, MIMO layers or #CSI processes. Option 2 is ‘nochange’. The comparison which is performed is to compare the gain of anMCG cell with the loss associated with diversion or modification of SCGcells.

The comparison is performed between the best options. In case a node hasmultiple alternatives for resolving the conflict, it only considers itsbest one. However, as the overall throughput picture is not considered,this scheme may result in somewhat sub-optimal result, when the overallthroughput is considered.

FIG. 19 shows a table illustrating various options in a dual conflictsituation, by referring back to the table in FIG. 17 .

In the first scenario, labelled ‘independent conflicts’ which mayinclude a scenario such as two independent choices of configuring Scellin LTE or NR (i.e. 2 sets of conflicting bands). Option 1 includes twosub-options:

-   -   1: Add SCG cell on 5B1 (and release MCG cell on 4B2)    -   2: Add SCG cell on 5Bm (and release MCG cell on 4Bn)

Option 2 includes two sub-options:

-   -   1: Keep MCG cell on 4B2 and not add SCG cell on 5B1    -   2: Keep MCG cell on 4Bn and not add SCG cell on 5Bm

In this scenario, each conflict can be handled separately and separatesignaling per conflict may be provided.

In the second scenario, labelled ‘Dependent conflicts’, which mayinclude the case of adding 2 LTE cells, resulting in both conflictingband and BC (involving same band). In more detail, the MCG has cell on4B2, SCG on 5B2. The SN wants to add cells on 5B1 and 5B3. Addition ofSCG cell on 5B1 results in band conflicts (with 4B2). Addition of SCGcells on 5B1 and 5B3 additionally results in conflict with 4BC1.

Option 1 includes 2 sub-options, with the highest throughput first:

-   -   1: Add SCG cells on 5B1 & 5B3 and divert MCG cell from 4B2 to        4B3    -   2: Add SCG cell on 5B1 and divert MCG cell from 4B2 to 4B3

Option 2 includes two sub-options:

-   -   1: Only add SCG cell on 5B3 (and not modify MCG)    -   2: No change

For sub-option 1, the SN should report the additional throughput ofadding both SCG cells (i.e. on 5B1 & 5B3). For sub-option 2, the SNshould report the additional throughput of a cell on 5B1.

In the third scenario labelled ‘Dependent conflicts’ which may involvetwo diversions with related side effects and where the best alternativefor the conflicts is not possible to configure together. Option 1includes 2 sub-options:

-   -   1: Add MCG cell on 4B2 and divert SCG cell 1 to 4B3 while        reducing SCG cell 2 MIMO layers    -   2: Add SCG cell on 5Bm divert SCG cell 1 to 4B3 while reducing        SCG cell×MIMO layers

In this case the SCG can choose its own preferred reconfiguration i.e.either initiate sub-option 1 or 2 within option 1. This may not resultin higher overall throughput though.

With regard to the table in FIG. 19 , for dependent conflicts, in case anode has multiple alternatives for resolving the conflict, it onlyconsiders its best one. Also, as the overall picture is not considered,this may result in a somewhat sub-optimal result.

Each side is able to determine if, from its perspective, the conflictscan be handled independently. The initiator only includes multipleconflicting reconfiguration if, from its perspective, they can behandled together. In case the receiving side cannot handle the multipleconflicts included in the requests, it only accepts part of them andrejects the others. It may accept requests resulting in highestthroughput. Within the response, the receiver may indicate that therejected requests may be retried immediately.

FIG. 20 shows a table setting how a continuous monitoring and selectionscheme for dealing with conflicting configurations may be implemented.Four different events are described, along with details of the resultingconfiguration, common aspects, RT per conflict and a single value forTotal Required Throughput, TRT.

The first event is an initial setup of IRAT BC of 4B1 and 5B1, whichresults in a configuration of 4B1+5B1. This requires a configured limitfor 5B1, as it introduces a potential conflict as configurationsincluding 4B2 cannot be configured in the future. As there is noalternative, a low value is set. The MN sets the RT for 5B1 to 5 Mbosand the TRT to 5 Mbps.

The second event is that the UE provides a measurement report indicatingthe availability of a suitable cell on 4B2. There is no change in theresulting configuration. As there is now a real alternativeconfiguration possible, the MN sets a more appropriate RT value of 20Mbps for 5B1, giving a TRT of 20 Mbps.

The third request is that the SN requests an SC addition on 5BC2,indicating it can achieve 250 Mbps for this BC. The resultingconfiguration is 4B3+5B1+5B2. The MN configures an additional limit i.e.it sets a realistic RT for 5BC2 (5B1+5B2), as it inhibits configurationof the real alternative 4BC5. Note that the MN needs to change Pcell toBC3 and it should have a measurement configured for this. The MN sets RTfor 5BC2 to 200 Mbps and the TRT becomes 220 Mbps.

The fourth event is that the rate that the MN can achieve for 5BC2 dropsto below 200 Mbps. The resulting configuration is 4B1+5B1 and the SNinitiates release of a cell on 5B2. The SN reports a failure andindicates AT per conflict of 25 Mbps for 5B1 and 200 Mbps for 5BC2. TheMN correspondingly initiates release of a cell on 5B2.

Note that in embodiments employing this scheme of signaling an RT valueper conflict, the SN may initiate release of the conflictingconfiguration in the case where its RT is not met. However, with the useof a single value of TRT, this is not possible since the SN is only ableto determine and report that the TRT is not met. It then needs toindicate AR per conflict to the MN to identify which action to take andso the resolution involves two separate steps.

Another embodiment concerns another solution for coordinating UEcapabilities in case of LTE 5G DC, namely by dynamic change of UEcapabilities. It is noted that for NR it has been agreed that the UE maydynamically change its UE capabilities. In particular, it may indicateto the network that some of its UE capabilities are temporarily notavailable. This dynamic change will only be supported for a few limitedcapabilities.

In this approach the UE indicates, after a change of a first RATconfiguration affecting the second RAT, to the network node controllingthe second RAT that its UE capabilities have changed. Also, with thisapproach it is possible to support negotiation between the network nodese.g. in case one node wishes to take larger portion of the UEcapabilities like configuring a conflicting band or BC.

A particular characteristic of this approach is that it involves nodirect communication between the network nodes involved Instead, the UEacts as an intermediary between the nodes. The solution does not requirethe network nodes to comprehend configuration or capability informationconcerning the other RAT.

FIGS. 21-23 relate to an embodiment whereby the capability coordinationis performed by dynamic change of the UE capabilities i.e. where the UEindicates that certain capabilities are suspended. E.g. the UE indicatesthat some of the available UE memory is suspended, or that it istemporarily not possible to configure some band or band combination.FIG. 21 shows a message exchange which shows an initial capabilitytransfer where the network, when requesting the UE to provide UEcapability information, may provide configuration parameters related todynamic capability update, such as a field indicating that dynamiccapability update is allowed or a prohibit timer controlling howfrequently the UE is allowed to indicate UE capability changes.

Typical examples of the capabilities that may be changed dynamically areas follows:

-   -   Available UE memory i.e. what is available to the MN may be        reduced if the SN requires more (i.e. shared memory);    -   The bands or band combinations i.e. the MN may not be able to        configure an LTE carrier on a particular frequency band anymore        because the SN wants to configure the UE with an NR carrier on        another particular frequency (e.g. same or conflicting one);

Note that embodiments of the invention recognize 2 particular basicdependency cases:

-   -   a) Shared resources e.g. memory. Here the MN can allocate a        portion or percentage to the SN based on negotiation; and    -   b) Conflicting resources e.g. bands. Here the MN needs to choose        between different competing options.

In response, the UE may indicate that certain capabilities are suspendedbecause, for instance, due to a configuration by the other RAT.

In FIG. 22 , the UE initiates a subsequent UE capability change inMessage 3 i.e. a new suspension or that a previously suspendedcapability is available again. The network may elect to accept thisrequest or reject it. If it elects to accept, then the network may needto change the current configuration (in Message 4). The latter, inparticular, applies in case the current radio configuration requires thecapabilities the UE wishes to suspend. E.g. the UE may wish to suspend aband currently used by one of its serving cells.

In FIG. 23 , the network requests resumption of a suspended capabilitywhich the UE may either accept or reject.

Alternatively, as shown in FIG. 24 , the UE may indicate that asuspended capability has become available again or can be resumed whichthe network may confirm, although this is optional.

FIGS. 25 and 26 illustrate how the dynamic change of UE capabilities maybe used to coordinate UE capabilities in case of LTE-NR DC. With thissolution, the network nodes can interact or negotiate without directinteraction and without having to comprehend capability or configurationinformation related to the other RAT.

This is because the UE performs the function of intermediary between theconnected nodes. Even though the UE is an intermediary, the network isstill in control of the configuration that results. In theseembodiments, there is no MN and SN, as each node is equal i.e. it is asymmetrical protocol. One node may imitate an action, while the othernode may reject it. In order to operate in this way, an associatedparameter is exchanged via the UE. The negotiation again uses acriterion, as before, e.g. some measure of throughput. Importantly,these embodiments honour the general principle that the configurationrespects the UE capabilities and no attempt is made to configure the UEin a way which it cannot support.

FIG. 25 shows a first and basic message exchange between the UE andfirst and second network nodes (NN1 and NN2). I.e. NN1 initiates aconfiguration that limits what NN2 can configure in future, but it doesnot require NN2 to adjust the current configuration.

The UE has a first radio connection (RC1) to a first node (NN1) using afirst Radio Access Technology (RAT1 e.g. LTE) and a second radioconnection (RC2) to a second node (NN2) using a second RAT (RAT2 e.g.NR, as in case of IRAT DC).

1: Now NN1 initiates a configuration that affects what NN2 can stillconfigure (e.g. it limits bands).

2. The UE provides an update of RAT2 UE capabilities to NN2 i.e. itindicates that certain capabilities are suspended (e.g. some bands, partof the L2 buffer).

3: NN2 confirms that it accepts the requested suspension of RAT2 UEcapabilities

4: The UE confirms the configuration as initiated by NN1 in message 1

Message 3 may not be needed in all cases, but may be used in case the UEinitiated suspension collides with an NN2-initiated reconfiguration thatrequires the use of RAT2 UE capabilities that the UE requests to besuspended.

There is no negotiation taking place here and hence no real need for anassociated parameter (throughput), although it could be useful to alwaysinclude such a parameter (to handle certain collision cases, asmentioned in the previous paragraph).

FIG. 26 illustrates the message exchanges between a UE and two networknodes, NN1 and NN2. In this particular case, NN1 wishes to initiate aconfiguration that requires that a certain suspended capability isresumed.

The messages are:

1. NN1 requests resumption of suspended RAT1 UE capabilities (i.e. alarger piece of the UE capabilities) and indicates the throughput gainit can achieve with the resumed capabilities.

2. The UE provides an update of UE capabilities to NN2 i.e. it requestssuspension of some of the UE capabilities (i.e. due to resumption inmessage 1), also forwarding the throughput gain indicated by NN1.

3. If the requested suspension results in a throughput reduction thatexceeds the throughput gain indicated in the suspension request, NN2accepts the requested suspension of UE capabilities. It provides aconfirmation, possibly with or after reconfiguring the UE, if thecurrent configuration towards NN2 cannot be maintained without thecapabilities that the UE requested to be suspended.

4. The UE confirms resumption of the RAT2 UE capabilities as requestedby NN1 in message 1.

5. NN1 initiates reconfiguration, making use of the RAT1 UE capabilitiesthat have been successfully resumed.

Unlike the scheme in FIG. 25 , this sequence supports negotiation. Forinstance, in case NN1 wishes to configure a cell on a band that is notsupported along with the current RC2.

In such a case, NN1 can indicate in message 1 the throughput that isgained if the cell would be configured or if the RAT1 UE capabilitywould be resumed. The UE includes this information when requesting NN2to suspend the conflicting RAT2 UE capabilities. If the throughputreduction due to suspending these RAT2 UE capabilities is less than theindicated throughput gain, NN2 is assumed to accept the suspensionrequest.

The UE does not confirm resumption (as in message 4) and NN2 does notconfirm suspension (as shown in message 3) before reconfiguring the UEaccording to the reduced UE capabilities. In other words, UEcapabilities should be respected at all times, and should avoidintroducing any special behavior for temporary cases.

In all embodiments, implementation is effected by means of programmedinstructions in the UE and/or the network nodes. FIG. 27 shows ageneralized form of network construction, whereby a UE 300 is in radiocommunication with a first node 100 and a second node 200. The first andsecond nodes are in communication with each other via a backhaulconnection. Depending on the particular embodiment of the presentinvention which is being implemented, the first node may be a masternode and the second node may be a secondary node. Alternatively, thenodes may operate according to a symmetrical protocol.

At least some of the example embodiments described herein may beconstructed, partially or wholly, using dedicated special-purposehardware. Terms such as ‘component’, ‘module’ or ‘unit’ used herein mayinclude, but are not limited to, a hardware device, such as circuitry inthe form of discrete or integrated components, a Field Programmable GateArray (FPGA) or Application Specific Integrated Circuit (ASIC), whichperforms certain tasks or provides the associated functionality. In someembodiments, the described elements may be configured to reside on atangible, persistent, addressable storage medium and may be configuredto execute on one or more processors. These functional elements may insome embodiments include, by way of example, components, such assoftware components, object-oriented software components, classcomponents and task components, processes, functions, attributes,procedures, subroutines, segments of program code, drivers, firmware,microcode, circuitry, data, databases, data structures, tables, arrays,and variables. Although the example embodiments have been described withreference to the components, modules and units discussed herein, suchfunctional elements may be combined into fewer elements or separatedinto additional elements. Various combinations of optional features havebeen described herein, and it will be appreciated that describedfeatures may be combined in any suitable combination. In particular, thefeatures of any one example embodiment may be combined with features ofany other embodiment, as appropriate, except where such combinations aremutually exclusive. Throughout this specification, the term “comprising”or “comprises” means including the component(s) specified but not to theexclusion of the presence of others.

Attention is directed to all papers and documents which are filedconcurrently with or previous to this specification in connection withthis application and which are open to public inspection with thisspecification, and the contents of all such papers and documents areincorporated herein by reference.

All of the features disclosed in this specification (including anyaccompanying claims, abstract and drawings), and/or all of the steps ofany method or process so disclosed, may be combined in any combination,except combinations where at least some of such features and/or stepsare mutually exclusive.

Each feature disclosed in this specification (including any accompanyingclaims, abstract and drawings) may be replaced by alternative featuresserving the same, equivalent or similar purpose, unless expressly statedotherwise. Thus, unless expressly stated otherwise, each featuredisclosed is one example only of a generic series of equivalent orsimilar features.

The invention is not restricted to the details of the foregoingembodiment(s). The invention extends to any novel one, or any novelcombination, of the features disclosed in this specification (includingany accompanying claims, abstract and drawings), or to any novel one, orany novel combination, of the steps of any method or process sodisclosed.

What is claimed is:
 1. A method performed by a first base station of afirst radio access technology (RAT) in a communication system, themethod comprising: transmitting, to a terminal, a first message torequest capability information of the terminal for a RAT type of aninter-RAT dual connectivity (DC), wherein the inter-RAT DC between thefirst base station of the first RAT and a second base station of asecond RAT is configured for the terminal; receiving, from the terminal,a second message including the capability information of the terminalfor the RAT type; transmitting, to the second base station of the secondRAT, a third message including the capability information of theterminal and information on a configuration restriction to be configuredby the second base station of the second RAT for the terminal; andreceiving, from the second base station of the second RAT, a fourthmessage as a response to the third message, wherein the configurationrestriction is associated with a band combination and identified basedon the capability information of the terminal.
 2. The method of claim 1,wherein the capability information of the terminal includes informationon at least one band combination supported by the terminal for the RATtype, and wherein the configuration restriction includes an indexindicating the band combination among the at least one band combination.3. The method of claim 1, wherein the fourth message includesmodification request information for requesting a modification for theconfiguration restriction, wherein the modification request informationincludes an index of a band combination requested by the second basestation of the second RAT, and wherein the first RAT includes evolveduniversal mobile telecommunications system terrestrial radio access(E-UTRA) and the second RAT includes a new radio (NR).
 4. A methodperformed by a second base station of a second radio access technology(RAT) in a communication system, the method comprising: receiving, froma first base station of a first RAT, a first message includingcapability information of a terminal and information on a configurationrestriction to be configured for the terminal; and transmitting, to thefirst base station of the first RAT, a second message as a response tothe first message, wherein the capability information of the terminal isfor a RAT type of an inter-RAT dual connectivity (DC), wherein theinter-RAT DC between the first base station of the first RAT and thesecond base station of the second RAT is configured for the terminal,and wherein the configuration restriction is associated with a bandcombination and identified based on the capability information of theterminal.
 5. The method of claim 4, wherein the capability informationof the terminal includes information on at least one band combinationsupported by the terminal for the RAT type, and wherein theconfiguration restriction includes an index indicating the bandcombination among the at least one band combination.
 6. The method ofclaim 4, wherein the second message includes modification requestinformation for requesting a modification for the configurationrestriction, wherein the modification request information includes anindex of a band combination requested by the second base station of thesecond RAT, and wherein the first RAT includes evolved universal mobiletelecommunications system terrestrial radio access (E-UTRA) and thesecond RAT includes a new radio (NR).
 7. A method in a communicationsystem which comprises a first base station of a first radio accesstechnology (RAT), a second base station of a second RAT, and a terminalconfigured with an inter-RAT dual connectivity (DC) between the firstbase station of the first RAT and the second base station of the secondRAT, the method comprising: receiving, by the terminal from the firstbase station of the first RAT, a first message to request capabilityinformation of the terminal for a RAT type of the inter-RAT DC;transmitting, by the terminal to the first base station of the firstRAT, a second message including the capability information of theterminal for the RAT type; transmitting, by the first base station ofthe first RAT to the second base station of the second RAT, a thirdmessage including the capability information of the terminal andinformation on a configuration restriction to be configured by thesecond base station of the second RAT for the terminal; andtransmitting, by the second base station of the second RAT to the firstbase station of the first RAT, a fourth message as a response to thethird message, wherein the configuration restriction is associated witha band combination and identified based on the capability information ofthe terminal.
 8. The method of claim 7, wherein the capabilityinformation of the terminal includes information on at least one bandcombination supported by the terminal for the RAT type, and wherein theconfiguration restriction includes an index indicating the bandcombination among the at least one band combination.
 9. The method ofclaim 7, wherein the fourth message includes modification requestinformation for requesting a modification for the configurationrestriction, wherein the modification request information includes anindex of a band combination requested by the second base station of thesecond RAT, and wherein the first RAT includes evolved universal mobiletelecommunications system terrestrial radio access (E-UTRA) and thesecond RAT includes a new radio (NR).
 10. A first base station of afirst radio access technology (RAT) in a communication system, the firstbase station comprising: a transceiver; and a controller coupled withthe transceiver and configured to: transmit, to a terminal, a firstmessage to request capability information of the terminal for a RAT typeof an inter-RAT dual connectivity (DC), wherein the inter-RAT DC betweenthe first base station of the first RAT and a second base station of asecond RAT is configured for the terminal, receive, from the terminal, asecond message including the capability information of the terminal forthe RAT type, transmit, to the second base station of the second RAT, athird message including the capability information of the terminal andinformation on a configuration restriction to be configured by thesecond base station of the second RAT for the terminal, and receive,from the second base station of the second RAT, a fourth message as aresponse to the third message, wherein the configuration restriction isassociated with a band combination and identified based on thecapability information of the terminal.
 11. The first base station ofclaim 10, wherein the capability information of the terminal includesinformation on at least one band combination supported by the terminalfor the RAT type, and wherein the configuration restriction includes anindex indicating the band combination among the at least one bandcombination.
 12. The first base station of claim 10, wherein the fourthmessage includes modification request information for requesting amodification for the configuration restriction, wherein the modificationrequest information includes an index of a band combination requested bythe second base station of the second RAT, and wherein the first RATincludes evolved universal mobile telecommunications system terrestrialradio access (E-UTRA) and the second RAT includes a new radio (NR). 13.A second base station of a second radio access technology (RAT) in acommunication system, the second base station comprising: a transceiver;and a controller coupled with the transceiver and configured to:receive, from a first base station of a first RAT, a first messageincluding capability information of a terminal and information on aconfiguration restriction to be configured for the terminal, andtransmit, to the first base station of the first RAT, a second messageas a response to the first message, wherein the capability informationof the terminal is for a RAT type of an inter-RAT dual connectivity(DC), wherein the inter-RAT DC between the first base station of thefirst RAT and the second base station of the second RAT is configuredfor the terminal, and wherein the configuration restriction isassociated with a band combination and identified based on thecapability information of the terminal.
 14. The second base station ofclaim 13, wherein the capability information of the terminal includesinformation on at least one band combination supported by the terminalfor the RAT type, and wherein the configuration restriction includes anindex indicating the band combination among the at least one bandcombination.
 15. The second base station of claim 13, wherein the secondmessage includes modification request information for requesting amodification for the configuration restriction, wherein the modificationrequest information includes an index of a band combination requested bythe second base station of the second RAT, and wherein the first RATincludes evolved universal mobile telecommunications system terrestrialradio access (E-UTRA) and the second RAT includes a new radio (NR). 16.A communication system comprising: a terminal configured to receive,from a first base station of a first radio access technology (RAT) afirst message to request capability information of the terminal for aRAT type an inter-RAT dual connectivity (DC), and transmit, to the firstbase station of the first RAT, a second message including the capabilityinformation of the terminal for the RAT type, wherein the inter-RAT DCbetween the first base station of the first RAT and a second basestation of a second RAT is configured for the terminal; the first basestation of the first RAT configured to transmit, to the second basestation of the second RAT, a third message including the capabilityinformation of the terminal and information on a configurationrestriction to be configured by the second base station of the secondRAT for the terminal; and the second base station of the second RATconfigured to transmit, to the first base station of the first RAT, afourth message as a response to the third message, wherein theconfiguration restriction is associated with a band combination andidentified based on the capability information of the terminal.
 17. Thecommunication system of claim 16, wherein the capability information ofthe terminal includes information on at least one band combinationsupported by the terminal for the RAT type, and wherein theconfiguration restriction includes an index indicating the bandcombination among the at least one band combination.
 18. Thecommunication system of claim 16, wherein the fourth message includesmodification request information for requesting a modification for theconfiguration restriction, wherein the modification request informationincludes an index of a band combination requested by the second basestation of the second RAT, and wherein the first RAT includes evolveduniversal mobile telecommunications system terrestrial radio access(E-UTRA) and the second RAT includes a new radio (NR).